The invention relates to a process and to an apparatus for storing stackable, sheet-like blanks which are delivered individually one after the other, in particular for packaging.
It is known, for example in order to produce packaging, to coat and/or to print on an elongate material web which runs through a cutting device, and in which the web is cut into individual blanks each suitable for producing a packaging unit. These sheet-like blanks are then bound to form stacks and, as such, are transported to a usually remote device, in which the individual blanks are conveyed away one after the other from the respective stack, then folded to form a packaging unit in each case, and finally filled and sealed.
The procedure described above is disadvantageous in that the finished blanks have to be laboriously bound to form stacks for the purpose of transportation, in that only stacks of a limited height can be formed, this resulting in it being possible for the blanks to be transported only in a large number of small stack units, in that during further processing of the stacks, care has to be taken that the blanks are correctly oriented, and in that, before their further processing, the bound-together stacks first of all have to be freed of the elements holding them together.
An object of the invention is to provide a process and an apparatus of the type mentioned in the introduction, by means of which blanks can be gathered together in a simple manner to form transport units, each exhibiting as large a number of blanks as possible. This renders possible a simple further processing of the blanks which have been gathered together to form the transport units.
The above and other objects and advantages of the present invention are achieved by the provision of a process and apparatus which feeds the blanks individually one after the other to an intermediate store which comprises a stack of the blanks. The blanks are then withdrawn from the intermediate store and fed in an essentially continuous stream to a winding station, and at the winding station the stream of blanks is wound into a roll. The winding may be performed for example by the apparatus disclosed in U.S. Pat. Nos. 5,176,333 and 4,898,336.
By virtue of the measures according to the invention, the blanks delivered individually one after the other can be wound onto a winding core, which, in comparison with conventional stacks, can receive a considerably larger number of blanks. In this manner, handling of the stored blanks is considerably simplified since, instead of a multiplicity of small stacks, only a small number of wound winding cores needs to be transported from the unit which produces the blanks to the unit which further processes the blanks.
In accordance with the present invention, the winding cores bearing the blanks can be deposited, for example, on pallets and transported by means of a fork lift truck.
After unwinding of the blanks stored on the winding cores, the empty winding cores can be re-used for storing new blanks. In this respect too, there is an advantage over the prior conventional procedure since the material by means of which the prior transport stacks were held together could not be directly re-used as such.
If it is ensured, according to the invention, that the blanks are fed to the individual winding cores with basically the same orientation, for example with their upper edge in front, it is furthermore ensured that the blanks stored on the winding cores are also conveyed, correctly oriented, to a further-processing unit since the blanks can be unwound in only one direction, for which reason the orientation of the blanks conveyed away from the winding cores is clearly determined by the orientation of said blanks during winding up.
By virtue of storing blanks on winding cores, it is, in addition, possible to produce a continuous blank stream leading to a further-processing unit, since the further-processing unit can be coupled to an unwinding apparatus, which exhibits, for example, two roll mounts which can optionally be used for charging the further-processing unit. It is thus possible always for one roll to ensure the feed of blanks to the further-processing unit, while the other, already previously emptied roll is exchanged for a new, full roll. By means of a corresponding switch designed, for example, in accordance with U.S. Pat. No. 5,158,278, it can, in this arrangement, be ensured that the beginning of the blank stream of one roll adjoins the end of the blank stream of the other roll without interruption.
An apparatus for unwinding the blanks stored on the winding cores may be designed, for example, in accordance with U.S. Pat. Nos. 5,158,242 and 4,898,336.
According to the invention, the blanks, occurring individually one after the other, are fed, before being wound up onto the winding core, to an intermediate store designed, in particular, as a blank stack.
The provision of the intermediate store permits separation of the blank stream leading, for example, from a cutting device to the intermediate store and the blank stream leading from the intermediate store to the winding core. This separation results in the situation where the blank stream leading to the intermediate store and the blank stream running away from the blank store can run at different speeds, in particular even a brief interruption in the blank stream delivering the blanks to the intermediate store not being detrimental.
There is consequently no need for high-outlay synchronization of the winding apparatus with the unit providing the blank stream, for example a cutting device. By virtue of the intermediate store, designed as a blank stack, a uniform and continuous blank stream leading to the winding core can thus be produced, irrespective of speed fluctuations or interruptions in the blank stream leading to the intermediate store.
Furthermore, the inclusion of the intermediate store, designed as a blank stack, can effect correct alignment of the intermediately stored blanks since the blanks, delivered, for example, in a non-precisely aligned manner from a cutting device, can be guided into a defined position by corresponding guide elements provided at the blank stack, as a result of which a precisely aligned blank stream running away from the intermediate store can be produced.
In addition, the blank stack, serving as intermediate store, also makes it possible for the blanks, initially occurring individually one after the other, to be made into an imbricated stream, in the case of which the successive blanks overlap in certain areas. The mode of functioning of such a stacking device is explained in more detail hereinbelow with reference to the figures.
By virtue of an imbricated stream fed to the winding core, it is possible to drive the winding core at low speeds since, with the provision of an imbricated formation, more blanks can be fed to the winding core per unit of time than with the provision of a blank stream with blanks arranged individually one after the other. In this arrangement, the closer the selected imbrication spacing, the lower the speeds of rotation of the winding core can be. In this arrangement, the winding-band length may also be shorter.
During winding up of the blanks onto a winding core, it is advantageous to have the narrower side of the blanks run in a circumferential direction of the winding core since only slight bending of the individual blanks takes place during winding up. This can be achieved, for example, in that the conveying belts running away from the intermediate store are arranged perpendicularly to the conveying belts leading to the intermediate store.